1. Field of the Invention
The invention relates to a rotary joint with a device configured to improve the electromagnetic properties and/or the shielding of the rotating transmission devices used in the rotary joint, as well as to a method for improving the electromagnetic properties and/or the shielding of the rotating transmission devices inserted in the rotary joint.
2. Description of Relevant Art
Rotary joints in general and, specifically, sliprings are used to transmit electrical signals between components that are rotatable with respect to each other. Here, at least one brush slides on a sliding track that is rotatable against the brush. Alternatively or additionally, both the electrical transmission of supply power and the electrical transmission of control and data signals based on contactless transmission (realized with rotating transformers as well as capacitive, optical or wireless data links, such as WLAN) may be realized. During such transmission, measures must be taken to shield the signal transmission path from interference influences from outside, and to meet the legal requirements concerning the exposure to electromagnetic radiation of persons in the circumference of transmission links. For this purpose, usually shield structures made from metal are used for shielding electromagnetic radiation.
U.S. Pat. No. 4,980,516 discloses, the use of flexible conductive gaskets for the purpose of sealing metal housing structures that are often used as shielding. Such gaskets are configured to prevent the formation of slot antennas and to compensate unevenness of the housing structures in edge regions, and thus to generate mechanical tightness. An adaptation of conductive gaskets for rotary applications is not practical because these would hinder the rotational movement and cause a massive debris contamination of the machine with generated abrasive particles.
U.S. Pat. No. 5,286,318 describes a shielding structure made of non-conductive layers and conductive layers. By using this measure, the volume of materials and thus the costs for fully enclosing housing structures made of copper or aluminum are reduced while keeping mechanical characteristics substantially unchanged.
The technical implementation of such an embodiment employing conductive and non-conductive layers causes the production process to be time-consuming and thus cost-consuming. To produce such a shielding structure, the application of multiple layers of conductive material on layers of the non-conductive support material in several production steps is required.